Dotan rudders do have three positions: Up, down, and stuck half-way in-between. In the latter position you must grab the blade and push/pull it past the pivot-point.

The weak link is the adjustable upper gudgeon, which is held in place by four small screws and has the tendency to rip off. If you're lucky, it rips off when you're beaching the boat. If it rips off while you're flying a hull, the forces on the rudder cause it to twist about parrallel to the water's surface. This means the lower gudgeon (which is very stout) twists the bolts that mount it to the hull right through the transom of your boat.

I've busted 2 or 3 upper gudgeons on my G-Cat 5.7M, my friend broke 2 on his P18-2. He's switched to the TheMightyHobie18 system and now that I've re-glassed the inside of my transoms, I'll be doing the same.

I think they would be excellent for dingys: Optimists, Lasers, etc.